CREATE SCHEMA monitoring;
alter schema monitoring owner to postgres;
create view monitoring.v_defrag as
SELECT
  current_database(), schemaname, tablename, /*reltuples::bigint, relpages::bigint, otta,*/
  ROUND((CASE WHEN otta=0 THEN 0.0 ELSE sml.relpages::FLOAT/otta END)::NUMERIC,1) AS tbloat,
  CASE WHEN relpages < otta THEN 0 ELSE round(bs*((sml.relpages-otta)::bigint)/1024/1024,1) END AS wastedMBytes,
  iname, /*ituples::bigint, ipages::bigint, iotta,*/
  ROUND((CASE WHEN iotta=0 OR ipages=0 THEN 0.0 ELSE ipages::FLOAT/iotta END)::NUMERIC,1) AS ibloat,
  CASE WHEN ipages < iotta THEN 0 ELSE round(bs*((ipages-iotta)/1024/1024)::bigint,1) END AS wastediMBytes
FROM (
  SELECT
	schemaname, tablename, cc.reltuples, cc.relpages, bs,
	CEIL((cc.reltuples*((datahdr+ma-
  	(CASE WHEN datahdr%ma=0 THEN ma ELSE datahdr%ma END))+nullhdr2+4))/(bs-20::FLOAT)) AS otta,
	COALESCE(c2.relname,'?') AS iname, COALESCE(c2.reltuples,0) AS ituples, COALESCE(c2.relpages,0) AS ipages,
	COALESCE(CEIL((c2.reltuples*(datahdr-12))/(bs-20::FLOAT)),0) AS iotta -- very rough approximation, assumes all cols
  FROM (
	SELECT
  	ma,bs,schemaname,tablename,
  	(datawidth+(hdr+ma-(CASE WHEN hdr%ma=0 THEN ma ELSE hdr%ma END)))::NUMERIC AS datahdr,
  	(maxfracsum*(nullhdr+ma-(CASE WHEN nullhdr%ma=0 THEN ma ELSE nullhdr%ma END))) AS nullhdr2
	FROM (
  	SELECT
    	schemaname, tablename, hdr, ma, bs,
    	SUM((1-null_frac)*avg_width) AS datawidth,
    	MAX(null_frac) AS maxfracsum,
    	hdr+(
      	SELECT 1+COUNT(*)/8
      	FROM pg_stats s2
      	WHERE null_frac<>0 AND s2.schemaname = s.schemaname AND s2.tablename = s.tablename
    	) AS nullhdr
  	FROM pg_stats s, (
    	SELECT
      	(SELECT current_setting('block_size')::NUMERIC) AS bs,
      	CASE WHEN SUBSTRING(v,12,3) IN ('8.0','8.1','8.2') THEN 27 ELSE 23 END AS hdr,
      	CASE WHEN v ~ 'mingw32' THEN 8 ELSE 4 END AS ma
    	FROM (SELECT version() AS v) AS foo
  	) AS constants
  	GROUP BY 1,2,3,4,5
	) AS foo
  ) AS rs
  JOIN pg_class cc ON cc.relname = rs.tablename
  JOIN pg_namespace nn ON cc.relnamespace = nn.oid AND nn.nspname = rs.schemaname AND nn.nspname <> 'information_schema'
  LEFT JOIN pg_index i ON indrelid = cc.oid
  LEFT JOIN pg_class c2 ON c2.oid = i.indexrelid
) AS sml;


ALTER view monitoring.v_defrag  OWNER TO postgres;


create function monitoring.f_defrag ()
  RETURNS SETOF monitoring.v_defrag AS
$BODY$
SELECT * FROM monitoring.v_defrag;
$BODY$
  LANGUAGE sql VOLATILE
  SECURITY DEFINER
  COST 100
  ROWS 1000;
ALTER FUNCTION monitoring.f_defrag()   OWNER TO postgres;




grant usage on schema monitoring to monitoring_role;
GRANT EXECUTE ON FUNCTION monitoring.f_defrag() TO GROUP monitoring_role;

check example

psql -U monitoring_user -d some_db -h localhost -c " select * from monitoring.f_defrag()  where ((tbloat>5 or ibloat >5) and wastedmbytes>100 or wastedimbytes >100) or wastedmbytes > 1024;"
 current_database | schemaname |   tablename    | tbloat | wastedmbytes |            iname             | ibloat | wastedimbytes
------------------+------------+----------------+--------+--------------+------------------------------+--------+---------------
 some_db          | pg_catalog | pg_largeobject |    1.6 |       2156.6 | pg_largeobject_loid_pn_index |    0.0 |             0